Balancing and walking using full dynamics LQR control with contact constraints

Sean Mason, Nicholas Rotella, Stefan Schaal, Ludovic Righetti

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Torque control algorithms which consider robot dynamics and contact constraints are important for creating dynamic behaviors for humanoids. As computational power increases, algorithms tend to also increase in complexity. However, it is not clear how much complexity is really required to create controllers which exhibit good performance. In this paper, we study the capabilities of a simple approach based on contact consistent LQR controllers designed around key poses to control various tasks on a humanoid robot. We present extensive experimental results on a hydraulic, torque controlled humanoid performing balancing and stepping tasks. This feedback control approach captures the necessary synergies between the DoFs of the robot to guarantee good control performance. We show that for the considered tasks, it is only necessary to re-linearize the dynamics of the robot at different contact configurations and that increasing the number of LQR controllers along desired trajectories does not improve performance. Our result suggest that very simple controllers can yield good performance competitive with current state of the art, but more complex, optimization-based whole-body controllers. A video of the experiments can be found at

Original languageEnglish (US)
Title of host publicationHumanoids 2016 - IEEE-RAS International Conference on Humanoid Robots
PublisherIEEE Computer Society
Number of pages6
ISBN (Electronic)9781509047185
StatePublished - Dec 30 2016
Event16th IEEE-RAS International Conference on Humanoid Robots, Humanoids 2016 - Cancun, Mexico
Duration: Nov 15 2016Nov 17 2016

Publication series

NameIEEE-RAS International Conference on Humanoid Robots
ISSN (Print)2164-0572
ISSN (Electronic)2164-0580


Other16th IEEE-RAS International Conference on Humanoid Robots, Humanoids 2016

ASJC Scopus subject areas

  • Artificial Intelligence
  • Computer Vision and Pattern Recognition
  • Hardware and Architecture
  • Human-Computer Interaction
  • Electrical and Electronic Engineering


Dive into the research topics of 'Balancing and walking using full dynamics LQR control with contact constraints'. Together they form a unique fingerprint.

Cite this